With popularization and development of household microwave ovens, more and more people begin to use the microwave oven to thaw frozen food because of advantages (such as fast speed and high efficiency) of the microwave oven.
At present, people usually do not eat bought food (such as meat, fish, etc.) all at once in daily life, and some of the food may be frozen for eating next time. Therefore it is necessary to study microwave thawing of food.
In order to study current situation of microwave thawing, 6 microwave ovens with different brands and different models are chosen from the market to thaw 500 grams of minced beef, and following results are obtained.
period ofmaximumminimumcookedBrandsModelsthawingfirepowertemperaturetemperaturediscolorationBrand 1Model 1 2′12″Automatic67.0° C.−2.2° C.YesBrand 2Model 215′00″Automatic29.6° C.−1.8° C.NoBrand 3Model 327′17″Automatic42.1° C.−0.5° C.YesBrand 4Model 4 7′00″Automatic48.2° C.−1.9° C.YesBrand 5Model 513′00″Automatic67.6° C.−1.3° C.YesBrand 6Model 611′00″Automatic41.9° C.−2.0° C.Yes
It can be seen from the above table that, microwave ovens of most brands have following problems. {circle around (1)} A period of thawing is long, in which the longest period is 27′17″. {circle around (2)} There is the cooked discoloration. {circle around (3)} A temperature difference is too large, in which the largest temperature difference reaches 69.2° C. The reason for occurring these problems is that an optimal temperature at thawing endpoint is not defined, thus lacking research on thawing procedures (such as firepower and period), and resulting in non-ideal effect of thawing. Therefore, it is urgent to research and improve the optimal temperature at thawing endpoint and a control method for thawing food by a microwave oven.